Recently, home wastewater treatment systems have become increasingly popular. Prior to the development of home wastewater treatment systems, septic tanks were the conventional manner of cleaning home and small commercial establishment wastes from the water. In view of the great cost associated with connecting a home sewage system with the city sewage system, it is economically beneficial to employ the use of home wastewater treatment systems. Present home wastewater treatment systems are a down-sized, underground version of the treatment processes employed by large central treatment plants.
Essentially, the treatment process correlates with an example found in nature. When a creek runs through rocks and over logs, turbulence is created and oxygen is captured. Aerobic bacteria utilize oxygen in their digestion processes. This allows the creek to purify itself. The home wastewater treatment systems simply employ a speeded-up version of this process in a manner known as "extended aeration". Air or oxygen is brought in by means of an efficient air pump and then diffused into thousands of tiny air bubbles by means of fine air diffusion. As these tiny bubbles move upward through the wastewater, oxygen is captured and the same purification process takes place. Such a system can allow normal household waste water to be reduced to a clear odorless liquid.
One such system has been manufactured and sold by Hydro-Flo Wastewater Treatment Systems, Inc. of P.O. Box 426, Kountze, Tex. The system is known as the "HYDRO-FLO" System. It is a self-contained automatic system. The HYDRO-FLO System incorporates two separate compartments, each performing a specific function in the digestion process. First, raw waste water enters the aeration compartment and is mixed with activated sludge and aerated. An air pump injects large quantities of air into this compartment by means of porous ceramic diffusers located above the perimeter of the aeration compartment. These diffusers create thousands of tiny air bubbles which provide oxygen for the aerobic digestion process and mixes the compartment's entire contents. These tiny bubbles provide better air-to-liquid contact so as to hasten the aerobic digestion process. Aerobic bacteria then use the oxygen in solution to break down the wastewater so as to convert the wastewater into an odorless liquid and gas. Hydraulic displacement causes the mixture to enter the second and final compartment. Due to the calm conditions and sloping walls of the clarification compartment, any remaining settleable material is encouraged to return to the aeration compartment for further treatment. The remaining effluent, upon reaching the outlet piping, is clear and odorless.
During a comprehensive eight month testing program, conducted by Baylor University, in accordance with the National Sanitation Foundation (NSF) Standard 40, the HYDRO-FLO Wastewater Treatment System produced an excellent effluent having a quality easily falling under the NSF Class I requirements of less than 30 PPM Bod (5 day) with greater than 85% reduction and less than 30 PPM TSS (Total Suspended Solids) with greater than 85% reduction. The actual HYDRO-FLO test averages were 7.23 PPM Bod (5 day) with 96.04% reduction and 5.89 PPM TSS with 96.81% reduction. The HYDRO-FLO System produced a clear and odorless effluent. Offensive, embarrassing wastewater odors, which are a common problem with septic tanks, are substantially eliminated by the HYDRO-FLO System.
This HYDRO-FLO System allows homes to e build on clay soil, rock or high water tables. This system also helps to protect the ground water supplies and eliminates gross pollution of ditches and streams. The effluent discharged from such a system is allowed by some state and local regulatory agencies to be discharged directly to a stream or pond or used to surface irrigate lawns and pastures. In areas where surface discharge is not allowed, subsurface disposal methods can be used with good success.
The aforedescribed HYDRO-FLO System essentially utilizes an air pump having an air line extending into a fiberglass tank. A number of drop lines are in communication with the air line and extend downwardly into the tank. An orifice is formed at the bottom of the drop lines. The porous ceramic diffuser is positioned around the orifice. This system is conventionally used for twenty-four (24) hour per day usage. When loaded to the maximum designed flow rate, the air pump operates continually to deliver air supplies to the aeration compartment within the fiberglass tank. As long as the air supply continues, there is no need to prevent the flow of mixed liquors into the drop lines. In addition, there is no need to overcome head pressures from any liquids that may have accumulated within the drop lines. However, it has been found that, with low level usage, it is not necessary to continually operate the air pump of the wastewater treatment system. It has been found possible to cycle the air pump on and off during the day.
Whenever the wastewater treatment system employs a cycling air pump the drop lines will tend to accumulate liquids. If the air pump is off and if enough time is provided, the drop lines will be filled with the "mixed liquors" until such liquids reach the level of the liquid within the fiberglass tank. When the air pump cycles on, it is necessary to apply suitable air pressure to exert a force on the accumulated liquids so as to force the liquids through the orifice at the bottom of the drop line and through the porous ceramic diffuser. As the mixed liquors are continually entering and leaving the porous ceramic diffusers and the orifices, there will be a tendency for small particles within the mixed liquor to plug the diffusers and to impede the operation of the system. The generation of unnecessary air pressure to force the liquids from the drop lines will require excessive energy to operate the air pump and reduce air pump life. Eventually, the diffuser which receives the least amount of air pressure from the air pump will be the first to clog completely. Whenever one of the diffusers becomes plugged, then an uneven distribution of aeration occurs within the wastewater in the tank.
Check valves have been applied to a variety of applications. Check valves are quite common in the process industries and in the automotive industries. Essentially, a check valve allows the flow of air or liquid in one direction while preventing the return flow of such air and/or liquid. One particular type of check valve has been found in the prior art (as shown in FIG. 7 herein) which is suitable for allowing the flow of air in one direction while, at the same time, preventing the flow of liquid from the opposite direction. Also, the check valve, of this type is generally suitable for slowing the leakage of air pressure from the opposite direction.
After use and experimentation, it was found that such a check valve, while appropriate for the purposes of the present invention, allows a high velocity of air to pass through relatively small restricted openings. In general, the greater the velocity of the air passing through the holes, the greater the amount of deflection and abrasion of the flap valve. It has been fund desirable to reduce the velocity of air which flows through the check valve.
It is an object of the present invention to provide an aeration apparatus having a check valve for preventing the accumulation of water in the drop lines.
It is another object of the present invention to minimize the plugging of the porous ceramic diffusers of an aeration system.
It is another object of the present invention to provide an aeration apparatus in which a check valve is easily accessible and serviceable.
It is another object of the present invention to provide an aeration apparatus which minimizes deflection and abrasion of a flap on a check valve.
It is still another object of the present invention to provide an aeration apparatus that is suitable for use on intermittently cycling air pumps.
It is still a further object of the present invention to provide an aeration apparatus which reduces the loads on the air pump.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.